Aerobic training consists of continuous exercise of relatively moderate intensity, which can range from low to strenuous, but long duration performed with the goal of improving and maintaining the fitness of the body's cardiovascular system, which includes the heart and the circulatory (pulmonary) system of arteries and veins. Commonly called cardio (short for cardiovascular), aerobic training means the majority of the energy used to perform such exercises is derived from the breathing in of oxygen. Such training is usually performed for at least 15 minutes at a heartrate level between 64% and 93% of the maximum heart rate suited for a person's age.
The purpose of aerobic training is to engage the body's heart, lungs, and circulatory system via repeated and continuous exercise to improve overall health, maintain fitness, and help prevent the development of obesity, hypertension, and cardiovascular disease. Regular aerobic exercise improves the efficiency of the functioning of the heart, lungs, and circulatory system. Aerobic/endurance training may be prescribed by a physician as therapy following a cardiovascular event (e.g., myocardial infarction) or cardiovascular surgery (e.g., angioplasty, heart transplant), or as a preventive intervention in patients at risk for developing cardiovascular disease due to hypertension, high blood cholesterol, or a family history of cardiovascular disease. Aerobic/endurance training may also be recommended to help overweight and obese patients lose and maintain body weight, or to help combat depression, anxiety, and/or stress.
A sedentary lifestyle and excess caloric consumption are the primary causes of overweight and obesity (extreme overweight); regular aerobic exercise is considered an important factor in controlling weight. Individuals who are overweight or obese are at higher risk of developing several medical conditions, including the following:
Clinical studies have shown that regular aerobic exercise has numerous benefits, including the following:
In addition, there have been reports linking aerobic exercise to a decrease in the risk of Alzheimer disease.
Physical exercise can be divided into aerobic and anaerobic. Anaerobic exercise is performed at a high intensity for a short time period. It usually involves a limited number of muscles in any given exercise. Weight lifting is one example of anaerobic exercise. Aerobic exercise (or aerobic/endurance training) involves light to moderate and upwards to vigorous physical activity that results in an elevated heart rate for a sustained period (long lasting).
Aerobic means with oxygen. Thus, the body is able to provide sufficient amounts of oxygen to the muscles for them to perform at various types of aerobic exercises. Energy used to power the muscles is derived aerobically when oxygen is used to metabolize nutrients from ingested foods.
For adults, aerobic exercise within a target heart rate range (calculated based on a maximum heart rate by age) is recommended. For healthy children, cardiovascular exercise that elevates the heart rate to no greater than a maximum heart rate of 200 beats per minute is recommended. Examples of light aerobic exercise are jogging and walking. More intense aerobic exercising includes long-distance running, swimming, and bicycling; cross-country skiing; recreational soccer or volleyball; and hiking on inclined terrain.
Unfortunately, Americans do not get enough physical activity (both aerobic and anaerobic). The President's Council on Fitness, Sports and Nutrition states that only one in three children are physically active on a daily basis. Further, fewer than one in five adults get at least 30 minutes of physical exercise each day. Over 80% of adult Americans do not meet the federal guidelines for aerobic and anaerobic exercises; the same percentage of adolescents do not attain the guidelines set for their age bracket.
Government guidelines for exercise are included in the 2008 Physical Activity Guidelines for Americans, which is provided by the U.S. Department of Health and Human Services. It recommends that children six to 17 years of age perform 60 minutes or more of physical activity daily. Specifically, this should be broken down into the following groups:
The federal guidelines recommend that adults 18 to 64 years of age should avoid inactivity, and that a little physical activity is much better than none at all. It specifically states:
Further, the guidelines recommend that adults 65 years of age and older should follow the adult guidelines whenever possible. When individuals are unable to follow them, they should be as physically active as “their abilities and conditions will allow.” It specifically states:
More specific recommendations for children, pregnant and lactating women, and older adults, as well as nutrition and caloric consumption information, are included in the Dietary Guidelines for Americans 2015–2020, which is provided by the U.S. Department of Agriculture (USDA).
A physical examination by a physician is important to determine if aerobic/endurance training is advantageous or detrimental. Prior to beginning exercise, a proper warm-up is necessary to prevent the possibility of injury resulting from tight muscles, tendons, ligaments, and joints. Appropriate warm-up exercises include walking, light calisthenics, and stretching.
Instruction on proper exercise form may be necessary for individuals inexperienced with aerobic exercise. Health care and fitness professionals, such as a certified personal trainer or physical therapist, can provide instruction on the proper form and frequency to achieve maximum benefits. These professionals may also perform a pre-exercise assessment of the individual's fitness to assist in designing an appropriate program.
If individuals are deconditioned, injured or recuperating from an injury, or have physical limitations, certain types of aerobic exercise may not be appropriate or achievable during the first few sessions, or ever. It is necessary to increase frequency and duration gradually before progressing to more vigorous activity.
Proper cool-down after exercise is important and should include a gradual decrease in exercise intensity to slowly return the heart rate to the normal range, followed by stretches to increase flexibility and reduce the likelihood of muscle soreness. Vigorous activities that cause sweating require that lost fluids are replaced by drinking water during and after the activity. Nutritious foods can also help to replenish nutrients used for energy during exercise.
Improper warm-up can lead to muscle strains, soreness, and other injuries. Overexertion without enough recovery time between exercise sessions also can lead to muscle strains, resulting in inactivity due to pain. Some individuals may be susceptible to exerciseinduced asthma. Dehydration is a risk during longer activities that involve sweating; water should be available and consumed during and after activities that cause prolonged sweating.
Significant health benefits are obtained by including at least a moderate amount of physical exercise for 30 to 60 minutes daily. Regular physical activity plays a positive role in preventing disease and improving overall health. Numerous medical studies show that aerobic exercise is beneficial for overall health and fitness.
Type 2 diabetes can be prevented with aerobic exercise. It helps to improve the body's ability to use insulin. The hormone insulin helps the body convert glucose (sugar) into energy. Exercise improves insulin resistance—a problem for people with diabetes. Cardiovascular disease risk is decreased with aerobic training because such exercise reduces blood pressure, lowers high cholesterol, and reduces other risk factors that contribute to disease progression. Aerobic exercises help to control weight by burning calories that would normally be stored as fat in a sedentary body.
For individuals just beginning an exercise program, results such as weight loss and increased endurance are noticeable in four to six weeks. For individuals with physical limitations or those recovering from surgery or injury, regular and appropriately prescribed and supervised aerobic training may alleviate pain, improve range of motion, and increase physical endurance.
The American College of Sports Medicine recommends that people who are overweight or obese start slowly when beginning an aerobic training program. Initially, about 150 minutes (2 hours, 30 minutes) of light to moderate exercise should be attempted per week. This amount of time should be increased slowly over many weeks and months so that 300 minutes (5 hours) or more of moderate aerobic exercise is eventually accomplished each week. Various types of aerobic exercise can be used to complete these goals. Iindividual exercise programs vary, and so do individuals' fitness level, age, and other important factors; therefore, these are only general recommendations. Specific instructions should be obtained from a family doctor. A trusted sports exercise expert may provide much needed encouragement and support to those who are beginning an exercise program.
For individuals under a physician's care who are prescribed aerobic training as therapy, supervision by an exercise physiologist, physical therapist, sports medicine professional, physical therapist assistant, or other healthcare professional experienced in rehabilitation and therapeutic exercise may be required. Aerobic training under such supervision is usually performed in a hospital rehabilitation department, an outpatient physical therapy center, or other medical fitness facility. Exercise professionals can also assist in designing appropriate aerobic training programs based on an individual's needs by performing initial fitness assessment tests and prescribing specific exercises that may address limitations or injuries.
See also Diabetes and exercise ; Senior fitness .
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Shape America (Society of Health and Physical Educators), 1900 Association Drive, Reston, VA, 20191-1598, (703) 476-9527, (800) 213-7193, http://www.shapeamerica.org .
Jennifer E. Sisk, MA
Revised by William A. Atkins, BB, BS, MBA